Disc drives are the primary devices employed for mass storage of computer programs and data used in computer systems. Within a disc drive, a load beam supports a hydrodynamic air bearing (or slider) proximate a rotating magnetic disc. The load beam supplies a downward force that counteracts the hydrodynamic lifting force developed by the air bearing. The slider carries a magnetic transducer for communicating with individual bit positions on the rotating magnetic disc. The combination of a slider and a transducer is generally called a head.
The load beam is coupled to an actuator arm which is, in turn, coupled to an actuator system. The actuator system positions the slider, and hence the transducer, relative to the disc to access desired tracks on the disc.
A gimbal structure is typically located between the load beam and the slider. The gimbal resiliently supports the slider and allows it to pitch and roll while it follows the topography of the rotating disc.
The use of a flex circuit head interconnect in the disc drive provides many advantages, such as lower costs, and increased robustness. With the current industry trend towards laptop and "notebook" computers, there has been a corresponding need to produce disc drives that are both incorporated in smaller packages and able to withstand the higher shock and vibration forces that are naturally to be expected when computers of this type are being carried from place to place. For example, some computer manufacturers demand that all sub-assemblies of their systems be able to withstand non-operating shock loads in the range of 300 g. A typical solution to the problem of large shock loads has been to ramp load and unload the heads, thus preventing "head slap" or potentially damaging contact between the heads and discs.
While ramp loading/unloading obviates the risk of damage due to head slap, such large shocks create another mode for potential failure. When read/write heads are ramp-parked off the surface of the disc, the only material supporting the slider itself is the relatively weak gimbal. Shock loads of 300 g have been shown to be large enough to permanently deform the gimbal, resulting in the inoperability of the entire disc drive.
In general, gimbal displacement limiters have been designed to limit the deflection of the gimbal away from the load point. Typically, these designs require special forming of the gimbal and/or load beam. As a result, their incorporation into modern disc drives requires additional fabrication to the gimbal and/or load beam, thus increasing costs.